After Cooper's Roost, you don't leave for MooShu. You firstly head to Santo Pollo for El Toro (yum, if you know what I mean :P), move back and forth between Big Sky, Cooper's Roost and Santo Pollo, then you head back to Skull Island (Port Regal) to do more tasks, then you head to Tumbleweed then to Haunted, and FINALLY after all that, you advance to MooShu.